ago no longer provides reliable protection. If you are under 45, it is much more likely that a round scar comes from the BCG tuberculosis vaccine—routinely administered at birth in many countries outside the United States—rather than from the smallpox vaccine. The two are easily confused, as both can leave a similar mark.
Why did the vaccine leave a scar at all?
Unlike most modern vaccines, which are delivered via a simple injection, the smallpox vaccine was administered using a two-pronged needle dipped in a vaccine solution. This needle punctured
